1. Enlarged specialised region at front of spinal cord. Entire CNS surrounded by 3
protective membranes called meninges. CSF (cerebrospinal fluid) is enclosed by
the inner two meninges. In the brain CSF found in 4 cavities called ventricles (CSF
kept in motion by cilia). Respiratory gases, nutrients and metabolic wastes pass
between CSF and blood. Apart from nutritive and excretory function also supports
and protects nervous tissue against mechanical shock.
CEREBRUM - consists of two large dorsal structures called the cerebral hemispheres.
Composed of a thin outer layer of densely packed cells forming a region of grey
matter called the cerebral cortex. Beneath this is a central mass of white matter
composed of nerve fibres. [NB. opposite to spinal cord].
Joining left and right cerebral hemispheres is a broad nerve fibre tract called the
corpus collosum.
Surface area of cortex increased by numerous infoldings called convolutions.
Each hemisphere divided into 4 lobes: frontal parietal
temporal occipital
& 3 areas recognised according to their function:
Sensory receiving impulses from receptors (INPUT)
Association interpreting input, storing input and initiating a
response in the light of similar past experience. Involves
memory, learning and reasoning (ie intelligence).
Motor transmitting impulses to effectors (OUTPUT)
THALAMUS - centre of forebrain. Sensory information reaching cerebral
hemispheres first pass through thalamus which channels signals to appropriate
region.
HYPOTHALAMUS - below thalamus. Involved in homeostasis. Contains osmo and
thermo regulation centres. Also centres for initiation of feeding, drinking and
sleeping. Several hormones produced including oxytoxin, ADH and hormones
which control release of hormones from anterior pituitary.
Lying in the mid brain is a group of nerve fibres called the reticular formation.
Sensory pathways lead from spinal cord to reticular formation as well as directly to
forebrain. Forebrain doesn’t respond to sensory signals unless activated by
reticular formation, When reticular formation stops activating forebrain a state of
sleep follows.
biologyexchangecouk-shared-resource1832.doc Mark Rothery11/05/11

2. CEREBELLUM - concerned with co-ordination of body movement and maintenance of
posture.
MEDULLA OBLONGATA - ascending and descending nerve fibre tracts cross over from
left to right and vice versa. Regulates autonomic activities including heart rate,
blood pressure, ventilation rate, swallowing, sneezing, coughing, vomiting.
Functions of Brain
1) Receives impulses from sensory organs of body.
2) Sends motor impulses to muscles and glands.
3) In association centres it correlates various stimuli from various sense organs.
4) Association centres and motor areas co-ordinate body activities.
5) Stores information.
Cerebrum
Visual Sensory areas
Cerebellum
Medulla
Hypothalamus
Pituitary Gland
biologyexchangecouk-shared-resource1832.doc Mark Rothery11/05/11